25
ENG
“EVD ice” +0300038EN - rel. 1.1 - 23.04.2018
9.6 Alarm table
Alarm Red LED Cause of the alarm
Reset
Effects on control
Checks / Solutions
A1
flashes
Probe S1 faulty or set alarm range exceeded
automatic
Valve closed
Check the probe connections.
A2
flashes
Probe S2 faulty or set alarm range exceeded
automatic
Valve closed
Check the probe connections.
E1
flashes
MOP protection activated
automatic
Protection action already in progress Check parameter “MOP protection: threshold”
E2
flashes
LOP protection activated
automatic
Protection action already in progress Check parameter “LOP protection: threshold”
E3
flashes
LowSH protection activated
automatic
Protection action already in progress Check parameter “LowSH protection: threshold”
E4
flashes
Low suction temperature
automatic
No effect
Check the threshold parameter.
E5
flashes
Emergency closing
automatic
Valve closed
E6
flashes
Network error
automatic
Control based on DI
Check the wiring and that the pCO is on and
operating
E7
flashes
Ultracap module powered at low voltage or low
charge
automatic
No effect
Check the wiring, the power supply and that the
minimum recharge time has elapsed
E8
flashes
Emergency closing not completed
Manual
Valve closed
Press PRG/Set or set the corresponding supervisor
variable to 0
EE
on
steady
EEPROM operating and/or unit parameters
damaged
Replace the
driver / Con-
tact service
Total shutdown
Replace the driver/Contact service
Tab. 9.a
10. TROUBLESHOOTING
The following table lists a series of possible malfunctions that may occur when starting and operating the driver and the electronic valve. These cover the
most common problems and are provided with the aim of offering an initial response for resolving the problem.
PROBLEM
CAUSE
SOLUTION
The superheat value mea-
sured is incorrect
The probe does not measure correct values
Check that the pressure and the temperature measured are correct and that the probe position
is correct. Check the selection of pressure probe. Check the correct probe electrical connections.
The type of refrigerant set is incorrect
Check and correct the type of refrigerant parameter.
Liquid returns to the com-
pressor during control
The superheat set point is too low
Increase the superheat set point. Initially set it to 11 K and check that there is no longer return of
liquid. Then gradually reduce the set point, always making sure there is no return of liquid.
Low superheat protection ineffective
If the superheat remains low for too long with the valve that is slow to close, increase the low su-
perheat threshold and/or decrease the low superheat integration time. Initially set the threshold
3 °C below the superheat set point, with an integration time of 3-4 seconds. Then gradually lower
the low superheat threshold and increase the low superheat integration time, checking that the-
re is no return of liquid in any operating conditions.
Stator broken
Enable the manual positioning and check the opening and closure of the valve.
Valve stuck open
Check if the superheating is always low (<2 °C) with the valve position permanently at 0 steps. If
so, set the valve to manual control and close it completely. If the superheat is always low, check
the electrical connections and/or replace the valve.
The “valve opening at start-up” parameter is too
high on many cabinets in which the control set
point is often reached (for multiplexed cabinets
only)
Decrease the value of the “Valve opening at start-up” parameter on all the utilities, making sure
that there are no repercussions on the control temperature.
Liquid returns to the
compressor only after de-
frosting (for multiplexed
cabinets only)
The superheat temperature measured by the dri-
ver after defrosting and before reaching operating
conditions is very low for a few minutes
Check that the LowSH threshold is greater than the superheat value measured and that the cor-
responding protection is activated (integration time >0 s). If necessary, decrease the value of the
integration time.
The superheat temperature measured by the
driver does not reach low values, but there is still
return of liquid to the compressor rack
Set more reactive parameters to bring forward the closing of the valve: increase the proportional
factor to 30, increase the integration time to 250 s.
Many cabinets defrosting at the same time
Stagger the start defrost times. If this is not possible, if the conditions in the previous two points
are not present, increase the superheat set point and the LowSH thresholds by at least 2 °C on
the cabinets involved.
The valve is significantly oversized
Replace the valve with a smaller equivalent.
Liquid returns to the com-
pressor only when star-
ting the controller (after
being OFF)
The “valve opening at start-up” parameter is set
too high
Check the calculation in reference to the ratio between the rated cooling capacity of the evapo-
rator and the capacity of the valve; if necessary, lower the value.
The superheat value
swings around the set
point with an amplitude
greater than 4°C
The condensing pressure swings
Check the controller condenser settings, giving the parameters “blander” values (e.g. increase the
proportional band or increase the integration time). Note: the required stability involves a varia-
tion /- 0.5 bars. If this is not effective or the settings cannot be changed, adopt electronic
valve control parameters for perturbed systems
The superheat swings even with the valve set in
manual control (in the position corresponding to
the average of the working values)
Check for the causes of the swings (e.g. low refrigerant charge) and resolve where possible.
The superheat does NOT swing with the valve set
in manual control (in the position corresponding
to the average of the working values)
As a first approach , decrease (by 30 to 50 %) the proportional factor. Subsequently try increasing
the integration time by the same percentage. In any case, adopt parameter settings recommen-
ded for stable systems.
The superheat set point is too low
Increase the superheat set point and check that the swings are reduced or disappear. Initially set
13 °C, then gradually reduce the set point, making sure the system does not start swinging again
and that the unit temperature reaches the control set point.
In the start-up phase with
high evaporator tempe-
ratures, the evaporation
pressure is high
MOP protection disabled or ineffective
Activate the MOP protection by setting the threshold to the required saturated evaporation tem-
perature (high evaporation temperature limit for the compressors) and setting the MOP integra-
tion time to a value above 0 (recommended 4 seconds). To make the protection more reactive,
decrease the MOP integration time.
Refrigerant charge excessive for the system or
extreme transitory conditions at start-up (for ca-
binets only).
Apply a “soft start” technique, activating the utilities one at a time or in small groups. If this is not
possible, decrease the values of the MOP thresholds on all the utilities.